Muskoxen—more akin to goats and sheep than to oxen—were introduced to Wrangel Island in 1975 and now number about 800. Increasingly, they cluster in tight groups to fend off a newly returned predator: wolves.

Wrangel’s sprawling gravel spits are home to large haul-outs of Pacific walruses, especially since climate change has made their preferred habitat—the ice pack—ever more tenuous. A healthy adult like this big female usually holds its own in a fight with a polar bear.

The summer thaw delivers plentiful food, like this washed-up walrus, to the bears of Wrangel Island. Despite new climate threats, bears remain what John Muir called the “master-existences of this ice-bound solitude.”

An arctic fox pup, just beginning to show its white winter coat, plays with a lemming carcass. Wrangel’s foxes subsist largely on these snow-burrowing rodents, whose numbers fluctuate wildly from year to year.